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potential localized interference from a 104.9 class A to a 105.3 rimshot

O

OKCRadioGuy

In the Oklahoma board several folks are asking why they get wiped out when fairly close to a 104.9's signal (running HD) while trying to listen to 105.3. They are listening (me included) on some pretty decent radios including a GM 'Bose' radio that normally has very good selectivity. My question to the group is do you think the HD signal is litterly wiping out the bottom edge of the 105.3 fairly weak signal or is it reciever capture over to the noise? According to the mask it appears the HD signal totally should stop at 105.15. Any ideas? http://radiomagonline.com/media/art/SpectrumMask.jpg

This is the intended station to receive:
http://www.radio-locator.com/cgi-bin/finder?call=KINB&sr=Y&s=C

This is the 'HD' station that seems to emitting the interference (legally I'm guessing):
http://www.radio-locator.com/cgi-bin/finder?call=Kkwd&sr=Y&s=C
 
The syptom seems to be that within about a half a mile of the 104.9 tower the 105.3 signal is swamped with noise similar to lack of signal, but not. (hiss)
 
Had the same issue with a 96.1/96.7 combination. 96.1 was 100kw, while 96.7 WAS a rimshot...anywhere within 5-7 miles of the 96.1 site, 96.7 was just clobbered.
 
In the OKC case, I'd imagine within 1 km of the tower site, the HD signal from 104.9 should have a signal of 60 dB or so on 105.15. (I didn't do the math. The way I understand it, it should be (analog power/10) propagated for 1km.) I'd be surprised if any receiver is good enough to filter a 60 dB signal on a first adjacent to tune a 40 dB signal on 105.3.
 
PTBoardOp94 said:
In the OKC case, I'd imagine within 1 km of the tower site, the HD signal from 104.9 should have a signal of 60 dB or so on 105.15. (I didn't do the math. The way I understand it, it should be (analog power/10) propagated for 1km.) I'd be surprised if any receiver is good enough to filter a 60 dB signal on a first adjacent to tune a 40 dB signal on 105.3.
Click to expand...

KKWD is 6kw at 100 m and KINB is 930 watts at 255 m. Within 1 km. The area of interference appears to be within the 60dbu protected contour of KINB. I would state that it appears this interference is not "legal" as it is within the 60. (If KKWD is generating it) The second part of this is the number of stations and the fact the interference is not identified as an HD signal. Listen on an HD radio at 104.9 and see if it captures.

I can't understand how the two are so close to start with. Class A stations typically aren't grandfathered unless there was an existing B spaced close and the stations went on as an A.

It appears both stations have the same footprint but KINB has much better height. This makes even less sense. KINB is being operated by a trustee (a receiver for court?) so I wonder if they are operating with an exciter or their real transmitter?

That kind of height (KINB) is normally great but allows multipath because of buildings. Do you have to hit a sweet spot to get the interference or is it continuous? Does it picket fence while driving?

Had a class A in Indy that had horrible multipath until we dropped it to 100 m. Signal improved greatly. Also went from an RCA (long story) single bay to a 4 bay half wave Jampro penetrator. We still had multipath but less than before. In parking garages, etc. The range of listening dropped in one area where terrain was an issue.

Isn't HD power still power/100? I didn't think the upgrade happened yet. The HD signals in Indy stink for the most part. I am 12 miles form the tower farm here and most of the HD's can be heard with an outdoor antenna. One station, after HD build, had a table top radio for staff to listen to. Couldn't hear the 50 kw station. (Running 13 kw at 1000 feet analog) (HD was 130w at 1000 feet digital) Studios were 7 miles maybe and at night you can see the tower near the studios.
 
"It appears both stations have the same footprint but KINB has much better height. This makes even less sense. KINB is being operated by a trustee (a receiver for court?) so I wonder if they are operating with an exciter or their real transmitter?"

They are full-power at slightly less than 1kw. The 'trust' is 104.9s owner but through the 'trust' to avoid the max number of station limit in the market. 105.3 is rented from the 'trust'.

"That kind of height (KINB) is normally great but allows multipath because of buildings. Do you have to hit a sweet spot to get the interference or is it continuous?"
It gets progressively worse as I get closer to their tower starting about a half a mile away.

"Does it picket fence while driving?"

Not too much. It's more of gradual ramp-up in hiss as I get closer to the stick. My guess is the HD is just too much for even our better radios adjacent channel, as several have suggested.

Thanks for the responses!
 
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